Does anyone remember Yahoo Pipes? That was awesome, I mostly used it (around 2008-2010) to make RSS for sites where it wasn't available https://en.wikipedia.org/wiki/Yahoo!_Pipes
I run one of those, https://pipes.digital. It supports scraping of sites that don't have RSS, creating a feed via xpath or css selectors. From the sites this cool project supports it has integrated support for Youtube and Twitter. But I think it would be a great extension to embed rssbox and offer blocks for all those services.